Method of oil quenching end-closed vessels



Feb, 1959 R. c. SHERWOOD ETAL 2,872,34

METHOD OF on QUENCHING END-CLOSED VESSELS Original Filed March 4, 1957 5 ew J m m w IHUI/M. m

4 g d K m PR3 United States METHOD OF OIL QUENCHING END-CLOSED VESSELS Robert C. Sherwood, Los Angeles, and Robert H. Lundquist, San Gabriel, Calif, assignors to California-Doran Heat Treating C0., Los Angeles, Calif., a corporation of California Original application March 4, 1957, Serial No. 643,813. Divided and this application February 21, 1958, Serial No. 719,466

5 Claims. 01. 148-2155) of rockets, aero-jet missiles, etc. require that the quenching step of the heat treatingthereof be performed in a manner to insure uniform cooling and, thereby, prevent variations in the texture of the metal walls thereof. Desired texture uniformity results in uniformity of stress conditions and elimination of weak spots or areas. The closed ends of such vessels present the greatest problem in that the metal thereof is not ordinarily quenched with the same degree of efliciency as the tubular walls of such vessels, primarily, because air'and gases are trapped in the closed ends of such vessels, as the same are lowered into the quench bath. Thus, the quenching liquid, usually oil, cannot achieve contact with the inner face of the closed end of a vessel with the undesirable results as above indicated.

By providing the vessel with a snorkel-type tube that extends within the vessel from the closed end through the open end and then upwardly alongside the vessel, air and gases ordinarily trapped are forced out by the oil entering the inside of the vessel. This manner of solving the problem, while in universal use, is faulty in that the vessel must be provided with means for affixing the tube and, after quenching, the same requires to be removed-an uneconomical procedurebut, what is of greater importance, the heated air and gases that are discharged from such tube are a great hazard and the same are known in the trade as a flame thrower. for that reason.

An object of the invention is to provide a novel oil quenching method for end-closed vessels in which the bath level is raised after the vessel has been lowered into the bath and circulation of the quenching oil is, thereby, set up to obtain rapid and efiicient quenching.

Another object of the invention is to provide a method, as above, in which the interior of the vessel being quenched while being lowered into a bath is evacuated of gas and air accumulations to effect such raising of the bath level within the vessel as to immerse all of the inner walls of the vessel.

A further object of the invention is to provide a method, as above, in which the mentioned gas and air evacuation is continued until the bath liquid is withdrawn to, thereby, effect lowering of the bath level to its initial level preparatory to repetition of the cycle of the present method.

The invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear inthe course of the following description. However, the drawing merely shows and the following description merely describes, one embodis atent O Patented Feb. 3, 1959 meat of the present invention, which is given by way of illustration or example only.

The figure is a semi-schematic view of apparatus according to the present invention.

The apparatus that is illustrated comprises, generally, a quench tank 5, an exhaust chest or chamber 6 disposed in the lower portion of tank 5, an airand liquid-exhausting tube 7 disposed in upright position in said tank and discharging into chamber 6, means 8 to pump material from chamber 6, a gas exhaust tube 9 to conduct oil, air

and gases from the chest and to vent the air and gases from the oil to atmosphere, an oil storage tank 10, a discharge pipe 11 into said tank and connected to the outlet of the pump means 8, a connection 12 between the tanks 5 and 10 to supply the former from the latter, and valve means 13 to control flow from tank 10 to tank 5.

The above generally-described apparatus is so located with respect to a fioor 14 that a vessel 15 may be conveniently lowered into tank 5, after the same has been heated in the initial steps of a heat-treating process, and as conveniently raised. The drawing shows a fixture 16 that, by means of hooks or rods 17, supports the vessel 15 in a depending position, and raising and lowering means 18 connected to the fixture and operable by overhead means. Also, the tank 5, near its upper end, is provided with fixture-engaging stop means 19 that limits the lower position of the fixture and of the vessel 15 carried thereby. The intent is to locate the vessel over tube 7 so that the closed end 20 of the vessel is spaced somewhat above the upper open end of said tube when the fixture is arrested by the stop means 19.

The chest or chamber 6 replaceably connects at 21 with the tube 7 so that the latter may be changed according to the diametr al size of the vessel to be quenched, thereby, assuring desired rapidity of flow through said tube. Thus, should the vessel 15 be substantially smaller than the one shown, a commensurately smaller tube 7 may be connected to chest 6 by the quick-change coupling 21.

The means 8 is shown asa centrifugal pump 22 that is under continuous operation by means of a motor 23 to draw material from both chest 6 and exhaust tube 9 and to discharge the liquid pumped thereby back into storage tank 10, while permitting discharge of gases from the end 24 of the discharge pipe 11.

The tube 9 vents to atmosphere from its upper end 25, the same being preferably located above the level of fioor'14.

The storage tank 10 is connected for gravity filling of quench tank 5 by means of connection 12, the valve means 13 controlling the same. Said means is here shown as a valve 26 in the bottom of tank 10, a valve actuator 27 that is shown in the form of an air-operated unit and capable of rapid action, and a connection 28 between valve 26 and unit 27.

Operation Assuming that the oil bath in tank 5 is at the level 29 slightly below the upper open end 30 of the tube 7: This level is approximately that of valve 26, when said valve isclosed. An additional quantity of oil 31 is stored in tank 10 above valve 26.

With the apparatus in the above-described condition, a heated vessel 15 required to be quenched for proper hardening is lowered into the bath over the tube 7. Since the motor 23 is continuously driving the pump 22, air and such gases that are given off from the oil are drawn into open end 30 of tube 7 and into chest 6. Thus, the level of oil inside the vessel 15 may rise to the level in tank 5. Part of this gas may exit directly from the end 25 of the tube 9 and part will be drawn into pump 22 and be forced through tube 11 out of the end 24 of the latter. Any

the bath level 29 and, therefore, not subject to the hardening phenomenon that results from a quick quench. At

that instant, unit 27 is operated to dump the oil-31through' the open valve 26 and through connection 12 into tank 5. Thus, the oil bath is raised to the level 32, well above the top of said closed end 20. Any time thereafter, the valve 26 may be again closed.

Since the pump 22 is operating, the level within the vessel 15 will rise until the oil therewithin rises above the end 30 of tube 7 and completely fills the interior of the vessel, thereby insuring complete and efficient quenching of all portions of the vessel. -As a result of this rise of level within the vessel, the oil will overflow the top of tube 7 and enter the chest 6. Some of this oil will rise in tube 9 seeking the level in tank 5; the remainder will be pumped upwardly into tank 10. According to the capacity of pump 22, the level in tube 9 will be diminished by said pump and the same will be kept exhausted as the level 32 in tank 5 is being lowered back to the initial level 29.

During the above reduction of level of oil, a flow downwardly along the outside of the vessel and upwardly within the vessel is efiected, further insuring that all portions of the walls of the vessel are uniformly treated by the oil as the heat therein is quenched.

When the level 29 is re-achieved, the apparatus is ready for another quenching operation, it being merely necessary to withdraw the quenched vessel and replace the same with one requiring quenching.

In other respects and with regard to time, temperatures of the bath, etc., usual quenching practice may be followed.

Itwill be understood that the aparatus and methodare not dependent. on use of 'oil in the bath, since water or other suitable liquids may serve as well. I

While the foregoing has illustrated and described what is now contemplated to be the best mode of carrying outour invention, the construction is, of course, subject to modification Without departing from the spirit and scope of the invention. It is, therefore, not desired to restrict the invention to the particular form of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described our invention, What we claim and desire to secure by Letters Patent is:

l. A method for quenching an end-closed vessel that consists in lowering the vessel, closed end up into a quench bath while simultaneously evacuating air and gases from within the vessel to allow the liquid of the bath to freely enter the interior of the vessel through the lower open end, arresting the lowering of the vessel before the closed end thereof becomes submerged in the bath, then, raising the level of the bath to cover said closed end and, at the same time, continuing evacuation of air and gases from the interior of the vessel and then evacuating quench liquid as said bath level raises, and finally, continuing liquid evacuation to restore the lower level in the bath and, thereby, completing the method cycle preparatory to repetition thereof.

2. A method according to claim 1 in which the material evacuated from the tank is separated into its liquid phase and is stored preparatory to being returned to the bath, and its air gas phase is vented to atmosphere.

3. A method for quenching an end-closed vessel that consists in lowering the vessel, closed end up into a quench bath while simultaneously evacuating air and gases from within the vessel to allow the liquid of the bath to freely enter the interior of the vessel through the lower open end, arresting the lowering of the vessel before the closed end thereof becomes submerged in the bath, then, raising the level of the bath to cover said closed end and, at the;

same time, continuing evacuation of air and gases from the interior of the vessel and then evacuating quench.

liquid as said bath level raises, such evacuation of quench liquid establishing a circulation of the bath liquid that is downward around the outside of the vesseland upward. within the interior of the vessel, and finally, continuing liquid evacuation to restore the lower level in the bath and, thereby, completing the method cycle preparatory to repetition thereof. 7 p p 4. A method according to claim 1 in which the air,

gases and liquid evacuation from the interior of the tanktakes place in close adjacency to the inner wall of the closed endpf the vessel, thereby circulating bath liquid against said wall. I

5. A method according to claim 3 in which the air, gases and liquid evacuation from the interior of the tank takes place in close adjacency to the inner wall of the closed end of the vessel, thereby circulating bath liquid against said wall.

1,936,719 Knerr Nov. 28, 1933 Weymar Feb. 5, 1907' 

1. A METHOD FOR QUENCHING AN END-CLOSED VESSEL THAT CONSISTS IN LOWERING THE VESSEL, CLOSED END UP INTO A QUENCH BATH WHILE SIMULTANEOUSLY EVACUATING AIR AND GASES FROM WITHIN THE VESSEL TO ALLOW THE LIQUID OF THE BATH TO FREELY ENTER THE INTERIOR OF THE VESSEL THROUGH THE LOWER OPEN END, ARRESTING THE LOWERING OF THE VESSEL BEFORE THE CLOSED END THEREOF BECOMES SUBMERGED IN THE BATH, THEN, RAISING THE LEVEL OF THE BATH TO COVER SAID CLOSED END AND, AT THE SAME TIME, CONTINUING EVACUATION OF AIR AND GASES FROM THE INTERIOR OF THE VESSEL AND THEN EVACUATING QUENCH LIQUID AS SAID LEVEL RAISES, AND FINALLY, CONTINUING LIQUID EVACUTION TO RESTORE THE LOWER LEVEL IN THE BATH AND, THEREBY, COMPLETING THE METHOD CYCLE PREPARATORY TO REPETITION THEREOF. 